Quarterly Financial Data (Unaudited) - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information [Line Items]
Impairment loss		$ 69,441		$ 39,700
Goodwill impairment loss		67,890
Intangible asset impairment loss		22,350	$ 20,800
Evanta [Member]
Quarterly Financial Information [Line Items]
Impairment loss	$ 69,400
Goodwill impairment loss	67,900
Intangible asset impairment loss	$ 1,500	$ 1,500